Log
QuestDB log provides database information. This page presents log level, their details, and where to configure and find the log.
Log location​
QuestDB open source​
QuestDB creates the following file structure in its root_directory:
questdb
├── conf
├── db
├── log
├── public
└── snapshot (optional)
Log files are stored in the log folder:
├── log
│  ├── stdout-2020-04-15T11-59-59.txt
│  └── stdout-2020-04-12T13-31-22.txt
Log levels​
QuestDB log provides the following types of log information:
| Type | Marker | Details | Default |
|---|---|---|---|
| Advisory | A | Startup information such as hosts, listening ports, etc. Rarely used after startup | Enabled |
| Critical | C | Internal database errors. Serious issues. Things that should not happen in general operation. | Enabled |
| Error | E | An error, usually (but not always) caused by a user action such as inserting a symbol into a timestamp column. For context on how this error happened, check for Info-level messages logged before the error. | Enabled |
| Info | I | Logs for activities. Info-level messages often provide context for an error if one is logged later. | Enabled |
| Debug | D | Finer details on what is happening. Useful to debug issues. | Disabled |
For more information, see the source code on GH.
Log examples​
The below is some examples of log messages by type.
Advisory:
2023-02-24T14:59:45.076113Z A server-main Config:
2023-02-24T14:59:45.076130Z A server-main - http.enabled : true
2023-02-24T14:59:45.076144Z A server-main - tcp.enabled : true
2023-02-24T14:59:45.076159Z A server-main - pg.enabled : true
Critical:
2022-08-08T11:15:13.040767Z C i.q.c.p.WriterPool could not open [table=`sys.text_import_log`, thread=1, ex=could not open read-write [file=/opt/homebrew/var/questdb/db/sys.text_import_log/_todo_], errno=13]
...
2022-08-23T07:55:15.490045Z C i.q.c.h.p.JsonQueryProcessorState [77] internal error [q=`REINDEX TABLE 'weather' COLUMN timestamp LOCK EXCLUSIVE;`, ex=
...
2022-11-17T10:28:00.464140Z C i.q.c.h.p.JsonQueryProcessorState [7] Uh-oh. Error!
Error:
2023-02-24T14:59:45.059012Z I i.q.c.t.t.InputFormatConfiguration loading input format config [resource=/text_loader.json]
...
2023-03-20T08:38:17.076744Z E i.q.c.l.u.AbstractLineProtoUdpReceiver could not set receive buffer size [fd=140, size=8388608, errno=55]
...
2022-08-03T11:13:41.947760Z E server-main [errno=48] could not bind socket [who=http-server, bindTo=0.0.0.0:9000]
Info:
2020-04-15T16:42:32.879970Z I i.q.c.TableReader new transaction [txn=2, transientRowCount=1, fixedRowCount=1, maxTimestamp=1585755801000000, attempts=0]
2020-04-15T16:42:32.880051Z I i.q.g.FunctionParser call to_timestamp('2020-05-01:15:43:21','yyyy-MM-dd:HH:mm:ss') -> to_timestamp(Ss)
2020-04-15T16:42:32.880657Z I i.q.c.p.WriterPool >> [table=`table_1`, thread=12]
2020-04-15T16:42:32.881330Z I i.q.c.AppendMemory truncated and closed [fd=32]
2020-04-15T16:42:32.881448Z I i.q.c.AppendMemory open /usr/local/var/questdb/db/table_1/2020-05/timestamp.d [fd=32, pageSize=16777216]
2020-04-15T16:42:32.881708Z I i.q.c.AppendMemory truncated and closed [fd=33]
Debug:
2023-03-31T11:47:05.723715Z D i.q.g.FunctionParser call cast(investmentMill,INT) -> cast(Li)
2023-03-31T11:47:05.723729Z D i.q.g.FunctionParser call rnd_symbol(4,4,4,2) -> rnd_symbol(iiii)
2023-03-31T11:47:05.723749Z D i.q.g.FunctionParser call investmentMill * 950399 -> *(LL)
2023-03-31T11:47:05.723794Z D i.q.g.FunctionParser call cast(1672531200000000L,TIMESTAMP) -> cast(Ln)
2023-03-31T11:47:05.723803Z D i.q.g.FunctionParser call cast(1672531200000000L,TIMESTAMP) + investmentMill * 950399 -> +(NL)
Log configuration​
QuestDB logging can be configured globally to DEBUG via either providing the
java option -Debug or setting the environment variable QDB_DEBUG=true. See
reference manual for details on
logging configuration.